Telephone and telegraph circuit



Nov.4, 1930. P. E. RITTER TELEPHONE AND TELEGRAPH CIRCUIT Filed Sept 27, 1929 Composite .Set

Repeater ATTORNEY Patented Nov. 4, 1930 j UNITED STATES.` PATENT IoI-#FICE V PAUL E. RITTER, E ROSELLEQNEW JERSEY, AssIGNoR To AMERICAN TELEPHONE VARI),TELEGRAEII coMrANY, n CORPORATION or NEW YoRx' TELEPHONE AND TELEGRAPII CIRCUIT Application-med september 27, 1929. seriai No. 395,628.

This invention relates to telephonesystems i of the well known four-wire type and morepartioularly to arrangements for utilizing the conductors of such systems for telegraph as well astelephone purposes. i The four-wire type of telephonel system A comprises two one-way line sections'each forv transmissionin opposite directions. Oneway repeaters would ordinarily be included loin these one-way line sections at various points.` `Furthermore,two one-way line sections `each transmitting in the same direction'. and being parts of different four-wire cir-v cuitsmight be arranged in quad relationship 15fand a phantom: telephone circuit produced from 4these two one-way line sections. `When the conductors in the quads in such a system were composited for telegraph service as wellf to cause singing or change of the gain. Such systems are well known in the prior art.

It has been found that in furnishing certain types of telegraph service,.suchrfor eX- yample as high speed printing telegraph service', over the above types of systems, that the by-pass coils will adversely affect the telegraph service; Accordingly it is one of the primary-objects of this invention to provide a novelfarrangement of the telegraph conductors fat a repeater point in such systems,

,tirely and the telegraph service may be ma terially improve-d. In the arrangements of the invention a telegraph circuit is not connected from the one-wa telephone circuit connected to the input o `a repeater element to the telephone circuit connected to the output of said repeater, butl thetelegraph circuitv is connected from the telephone circuit connected to the input of a repeater to the 50 one-way telephone circuit of the same fourwhereby the by-,pass coils may be omitted en-"J wire line connected to the input of a repeater for transmission in the oppositeV direction. In accordancewith the arrangements of this invention the points connected by the telegraph legs on the two pairs of conductors will be at approximately the same transmission level and any telephone energy which passes from one pair to another through the telegraph branches will cause no cross talk but only echo to a degree not materially undesirable. `Accordingly the arrangements'of the invention make it practicable to transfer a metallic telegraph, circuit atfan intermediate telephone repeater point from one pair of a four-wirecircuit to the other Vvpair with- .out the use of a by-pass set. Further objects `and features ofthe invention will appear more fully from the detailed description thereof hereinafter given. l A

The invention may be more fully understood from the following description, together with the accompanying drawing,.in the Figures l and 2 of which the invention is illustrated. Fig. l is a circuit Vdiagram illustrating a preferred embodiment of. the

invention. In Fig. 2 isillustrated schematically certain principles of'operation ofthe invention. Similar reference' `characters have'been utilized to denote like parts in both of the Vfigures. i ,I

In Fig. 1 there is shown a portion of two four-wire telephone systems together with thetelegraphconnections of this invention.

'One of the four-way telephone circuits will comprise the one-way line comprising :the

section L1 IV-E Vinterconnectedbythe re- V peaterRl with the line section L1 W-E. The other side of this four-wire circuit will comprise the line section Ll E-W connected by the repeater R3 with the line section L1 E-W. The other four-wire" circuit will comprise the line section L2 VV-E interconconnected by the repeaterIt2V with the line section L2 V-E. The other one-way rsection of this four-wire circuit will comprisethe f line section L2 VE---VV interconnected by the repeater Ri, with the line section Lf2 The line sections L1 W-E and L2 W-E are arranged in quad relationship and are phantomed to provide an additional `circuit which may be established through the repeater R-F1 and thence over the line sections L1 W-E and L2 Vif-E. Line sections L1 E-W and L2 E-W are arranged in a different quad and are phantomed to provide an additional circuit which may be established through the repeater R-FZ and thence over line sections L1 E-VV and L2 E-W When the line sections Ll VV--E and L2 W-E were to be utilized for telegraph pur` poses there might be provided, as indicated'in the dotted lines, the circuit 13, including the by-pass set 14. This circuit and by-pass set would readily allow the transmission of certain types of telegraph currents from one line section to the other and would serve to prevent the telephone currents from being transmitted from the output of the repeater back to theinput of the repeater to cause singing. In a similar manner the other line sections would be connected by the circuits such as 17, 15 and 19 which would include the bypass sets 18, 16 and 20 respectively,'and such arrangements have been indicated in dotted lines as they are old in the art. It has been found that in furnishing certain types of telegraph service, such for example as high speed printing telegraph service, that by-pass sets of this type will adversely affect the transmission of the telegraph signals. In accordance Vwith the arrangements of this in- Y ventionthe metallic telegraph circuit utilizing line section L1 W-E'will be extended through the composite set 5 over the circuit 21 through the composite set 11, and thence over the line section L1 E-V. In other words, the metallic telegraph circuit at the intermediate telephone repeater point is transferred from one pair ofa particular four-wire circuit to the other pair of said four-wire telephone circuit. In a similar manner circuit 22 would connect the composite set in line section L2 W-E with the composite set 12 in line section L2 E-,W.

Circuit 28 would connect line section L2 W--E with line section L2 E-V and circuit 24 would connect line section L1 W-E with line section L1 E-W It is pointed out that in all of these telegraph circuits the by-pass sets may be omitted.

Any telephone energy coming in from line section L1 W-E which might possibly be transmitted over circuit 21 would be transmitted through the repeater R3 and thence over line section Ll E-W back to the subscriber, and would cause an echo effect. However, this energy would not cause any cross talk effect. In a similar manner the other telegraph circuits might cause echo effects, but would not cause any cross talk effects. It has been found that the echo effects caused by such 'connections will not materially affect transmission.

In Fig. 2 the arrangements of Fig. 1 are shown schematically to illustrate why, in

accordance wit-h the arrangements of this invention, the telegraph connections are established between points of approximately the same transmission level. Let it be assumed that at point A, which would be at the input of the repeater on one side of the four-wire circuit, the transmission level would be -20 db. In accordance with the arrangements of this invention, the telegraph connection would bey established' by a circuit such as X between the telegraph legs of the input` composite sets on the two sides of the line. The loss through the composite sets and this connection increases with frequency and with a particular design commonlyused is about 60 d?) at 300 cycles. The transmission level at points A Vand B, for purpose of illustration, might ybe approximatelythe same, namely -20 db. If we assume that the repeaters give a gain of 30 ci?) at 300 cycles, the transmission level at points C and D will be .-l- 10 do. The energy at this frequency, which might cause echo effects, would then be only at 50 d?) when it arrives at the point D. This would Vnot cause serious echo effect. The above illustrates vthe way the arrangement works at one frequency. Though the repeater gain and the loss through the connection X vary with frequency, they may be so proportioned thatl excessive echo is not experienced at any frequency. Y r

twill be seen that the omission of the bypass sets will materially aid the transmission of the telegraph signals. Furthermore, when the connections are made between points of the saine transmission level from one pair of a four-wire circuit to the other pair, as shownv by this invention, no serious echo effects or cross talk will appear. While the arrangements ofthe invention have been shown as embodied in certain specific forms which are deemed desirable, it is understood that they are capable of embodiment in many and other widely varied forms Without departing from the spirit of the invention as defined in the appended claims.

What is claimed is:

1. A four-wire telephone circuit comprising two one-way line sections for transmission in opposite directions, repeaters in said one-way line sections, and a telegraph circuit connected between said one-way line sections at the inputs of said repeaters.

2. A four-wire telephone circuit comprising two one-way line sections for transmission in opposite directions, repeaters in said one-way line sections, and a telegraph circuit connected between said one-way line sections at the outputs of said repeaters.

3. A four-wiretelephone circuit comprising two one-way line sections for transmission in opposite directions, repeaters in said one-way line sect-ions, and a telegraph circuit connected between said one-way line sections at points thereon of about the same transmission level.

4:. A four-wire telephone circuit comprising two one-way line sections for transmis-Y sion in opposite directions, repeaters in said one-way line sections, a telegraph circuit connected between said one-way line sections at the inputs of said repeaters, and a second telegraph circuit connected between said one-way line sections at the outputsof said repeaters.

5. Two four-wire telephone circuits each having two one-way line sections with repeaters therein for transmission in opposite directions, the conductors of said one-way line sections for transmission in opposite directions being arranged in quads and phantomed at repeater points for the production of additional circuits, and telegraph conductors connecting the one-way line sections of each of said four-wire circuits together at points thereon of approximately the same transmission level.

In testimony whereof I have signed my name to this specification this 26th day of September, 1929.

v PAUL lE. RITTER. 

